raster data jduh/courses/geog492w12/week3b.pdf · pdf file 1 raster data analysis raster...

Click here to load reader

Post on 07-Aug-2020

4 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • 1

    Raster Data Analysis

    Raster Data Model

    • Cells (Pixels)

    • Cell value

    • x, y cell sizes

    • Geographic coordinates

    Attributes

  • 2

    Raster to Vector / Vector to Raster

    V2R

    R2V

    ArcGIS Spatial Analyst

    • Mainly for raster data analysis

    – Arctoolbox: Spatial Analyst Tools

    – Spatial Analyst Toolbar

    – Raster Calculator

  • 3

    Raster Calculator • Single-line map algebraic expression

    • Multiple inputs in a single expression.

    • Multiple Spatial Analyst tools in a single expression.

    Raster Calculator Syntax

    • Operators inraster1 + inraster2

    • Tools & Functions (tool names are case sensitive!) Aspect("C:/Datat/inraster")

    • Tool parameters Slope(“dem”, "PERCENT_RISE")

  • 4

    Spatial Analyst Option Menu (ArcGIS 9.x)

    Geoprocessing Environment Setting (ArcGIS 10)

  • 5

    Mask & Extent

    Raster Calculator Functions

    • Arcinfo

    Workstation /

    Arcdoc

    • > 200 functions

  • 6

    Raster Operations

    Local operation

    (majority)

    Focal operation

    (focalmajority)

    Zonal operation

    (zonalmajority)

    Global operation

    (costdistance)

    Application functions

  • 7

    Local Operator: Combine

  • 8

    Working with Nodata in RC

    • ISNULL: convert Nodata to a value

    • SETNULL: set cell value to Nodata

    • CON: conditional function

    • Examples

    – Replace Nodata with 0 in a DEM

    con(isnull([dem]), 0, [dem])

    – Set slope > 15 to Nodata on the DEM

    setnull([slope]> 15, [dem])

  • 9

    ISNULL() Function

    SETNULL() Function

  • 10

    CON() Function

    Raster Clip Example

    Output A Output B Output C

  • 11

    Raster Clip

  • 12

    Raster Buffering

    Point Features to Raster

    • Con( isnull(pointg), 0, 1)

  • 13

  • 14

    Implementing Ordered Weighted

    Average in ArcGIS

    • Raster Calculator

    r1 = rank(1, [factor1], [factor2], [factor3])

    r2 = rank(2, [factor1], [factor2], [factor3])

    r3 = rank(3, [factor1], [factor2], [factor3])

    owavg = [r1] * 0.5 + [r2] * 0.3 + [r3] * 0.2

View more